Froggy Paddle!

It's summer, and the school swimming pool is open for use. While Fuyuki has been dreading this all year (he can't swim), Keroro hatches a new scheme to infiltrate the swimming pool and have some fun on his own, resulting in a confrontation with Natsumi in the pool, where Keroro's amphibious advantage over her is exploited to the fullest.
After the historic Earth versus Keron Swimming Meet, a second interplanetary competition begins at nighttime, as humans and Keronians duel each other with the scariest ghost stories they can think of. While Fuyuki's little-known talent for ghost stories wins the day, the only real loser here is Giroro, who gets jerry-rigged to a meter and subjected to all the scares (and some physical violence) from both sides.